Valve controller, valve controlling method, refrigeration and cold storage system, device and method for controlling the system

ABSTRACT

To provide a motor-driven valve with a small number of parts, with excellent assemblage, capable of maintaining a large valve port diameter even downsized, and to prevent deterioration of housing environment due to sound caused by the impact and shortened life that are generated by collisions of closing limit stopper parts. A motor-driven valve according to the present invention comprises: a male screw member rotating in accordance with a rotation of a rotor of an electric motor and engaging with a female screw member fixed to a valve main body; a valve body contacting to and separating from a valve seat in the valve main body by a rotation of the male screw member; two stopper parts rotating in accordance with the rotation of the rotor of the electric motor; an opening limit stopper part mounted to the female screw member, the opening limit stopper part contacting with one of the two stopper parts in a fully-opened state of the motor-driven valve to restrict the rotation of the male screw member in a direction that the motor-driven valve opens; and a closing limit stopper part mounted to the female screw member, the closing limit stopper part contacting with another stopper part in a fully-closed state of the motor-driven valve to restrict the rotation of the male screw member in a direction that the motor-driven valve closes.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority to Japanese Patent ApplicationNo. 2009-8781 filed on Jan. 19, 2009, Japanese Patent Application No.2009-12838 filed on Jan. 23, 2009 and Japanese Patent Application No.2009-59796 filed on Mar. 12, 2009.

STATEMENT RE: FEDERALLY SPONSORED RESEARCH/DEVELOPMENT

Not Applicable

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a valve controller for controllingvalve opening of a motor-driven valve, particularly to a controller forvalve opening control when an abnormality occurs in a temperaturesensor, a pressure sensor and the like. In addition, the presentinvention relates to a valve controller and a valve controlling method,particularly to a controller and so on for controlling valve opening ofa motor-driven valve and others for adjusting flow rate of arefrigerant. Further, the present invention relates to a refrigerationand cold storage system used for a refrigeration and cold storage showcase and so on, and a device and a method for controlling the system,particularly to a refrigeration and cold storage system and the like inwhich operation/stoppage of a compressor is switched in accordance witha temperature of a controlled object.

2. Description of the Related Art

Conventionally, in a refrigeration cycle used for refrigeration and coldstorage show cases and the others, in order to accurately adjust flowrate of a circulating refrigerant, as an expansion valve for flowcontrol, a motor-driven valve with a pulse motor for moving a valve bodyhas widely been utilized. In this refrigeration cycle, generally, adegree of superheat is calculated after detecting inlet and outlettemperatures of an evaporator with temperature sensors, and valveopening of the motor-driven valve is controlled by comparing thecalculated degree of superheat with a preliminarily set degree ofsuperheat.

As described above, although the valve opening control of themotor-driven valve is performed based on the temperature detected by thetemperature sensor, at the operation of the refrigeration cycle, thereis a possibility that the temperature cannot appropriately be detectedwhen an abnormality occurs in the temperature sensor due todisconnection, short circuit and the like in operation, in such case, itbecomes impossible to continue the valve opening control of themotor-driven valve also. Then, in a conventional valve controller, inits manufacturing stage, a fully-closed value or a fully-opened value isset as an opening value for emergency, when an abnormality occurs in thetemperature sensor, the motor-driven valve is controlled to stop in thefully-closed or fully-opened state (see Patent document 1 as anexample).

But, when the motor-driven valve is stopped in the fully-closed state,after that, all the while, a refrigerant does not flow in therefrigeration cycle, so that the operation of the refrigeration cyclestops due to a low-pressure abnormality, which makes it impossible, asan example, to maintain inside temperature of a refrigeration and coldstorage show case low. As a result, until a maintenance worker arrives,the inside temperature remains high over a long period of time,resulting in bruised foods.

On the other hand, in case that the motor-driven valve is stopped in thefully-opened state, circulation of the refrigerant is not stopped butthe quantity of refrigerant fed to the evaporator becomes too much, sothat a refrigerant from the evaporator is returned to the compressor inthe form of liquid (liquid back). In this case also, the show casecannot be cooled in the same manner as described above, which may causebruised foods, moreover, there is a fear that the compressor is damagedthrough liquid compression.

These problems can be generated not only when an abnormality occurs inthe temperature sensor but in a pressure sensor for detecting pressureof a refrigerant circulating in the refrigeration cycle almost in thesame manner as described above, so that it has been a key problem toconsider a measure in case of abnormality in the sensors for detectingtemperature and pressure in the refrigeration cycle.

Further, conventionally, in refrigeration cycle systems used forair-conditioners, refrigeration and cold storage show cases, and thelike, flow rate of a circulating refrigerant is adjusted for thepurposes of stabilizing a cooling capacity, efficient operation, and thelike, and in order to accurately performing the adjustment, as anexpansion valve for controlling the flow rate, a motor-driven valve thatis a motor-driven expansion valve with a pulse motor for moving thevalve body has been widely utilized.

However, since the valve opening control of the motor-driven valve isgenerally performed with an open-loop control that doesn't feed back anabsolute opening (actual opening), in addition, when a power-supply tothe motor-driven valve is stopped, the valve body in the motor-drivenvalve stops at a position when the power-supply is stopped withoutreturning to an initial position, so that at and after the second apower-supply after the first supply, it is impossible to exactly graspan absolute opening (a position of the valve body) when the power-supplyis started.

Therefore, in the control of the motor-driven valve, generally, aninitialization processing is performed when power is supplied to thevalve, and the valve opening control is started after determining theinitial position of the valve body (for instance, see Patent document2). Here, it is the initialization processing to drive the motor-drivenvalve so as to be closed by applying the number of pulses over all thestrokes from the fully-opened state to the fully-closed state toforcibly change the valve opening of the motor-driven valve to that infully-closed state.

However, in the refrigeration cycle system, there is a possibility thatforeign substances such as impure substances are generated in arefrigerant flow passage, in the foreign substances, large ones can beremoved by a strainer and so on, but small ones may pass through thestrainer and flow into the inside of the motor-driven valve. In such acase, in the motor-driven valve are caught the foreign substances, whichmay cause a shift in the valve opening of the valve.

That is, in case that the catching of the foreign substance occurs,since the foreign substance prevents the valve body from moving, forexample, when a driving signal of 100 pulses are added to the pulsemotor, an actual amount to be driven becomes smaller than that whendriving the signal of 100 pulses are given. As a result, a difference ofseveral pulses is generated between a valve opening estimated from thenumber of pulses added to the motor-driven valve and an actual valveopening of the motor-driven valve itself, after that, the motor-drivenvalve is operated with the valve opening including the difference.

For this reason, it becomes impossible to accurately control the valveopening of the motor-driven valve, for instance, when a driving signalfor obtaining the fully-closed state is added to the motor-driven valve,the motor-driven valve is actually in a slightly-opened state. In thiscase, it is possible to generate a leak of a refrigerant and the like,resulting in deteriorated reliability of the device and so on.

Further, generally, in the refrigeration and cold storage show casesutilized for cold reserving and displaying foods and the like,operation/stoppage of the compressor is switched in accordance withhigh/low of the inside temperature, and the switching action is repeatedaccording to the change in the inside temperature, which controls theinside temperature to be maintained constant.

The switching of the operation/stoppage of the compressor is performedin such a manner that the compressor is operated at the moment that theinside temperature becomes higher or equal to a predetermined settingtemperature for turning the compressor on, and the operation of thecompressor is stopped at the moment that the inside temperature becomeslower or equal to a predetermined setting temperature for turning thecompressor off. A difference between the setting temperatures forturning the compressor on/off is called “DIFFERENTIAL”, which is set toavoid frequent operation/stoppage actions (hunting) of the compressor.

In addition, flow rate of a circulating refrigerant in the refrigerationcycle is adjusted for the purposes of stabilization of a coolingcapacity when cooling inside of a refrigeration and cold storageshowcase, efficient operation, and the like, and in order to accuratelyperformed the adjustment, as a flow control valve for the refrigerant, amotor-driven expansion valve with a pulse motor or the like has widelybeen used. In the refrigeration cycle with the motor-driven expansionvalve, a degree of superheat of a refrigerant flowing the evaporator isdetected, and the detected degree of superheat is compared with asetting degree of superheat, and in accordance with the difference, theflow rate of the refrigerant is controlled through adjustment of thevalve opening of the motor-driven expansion valve using a PID controland others.

By the way, as described above, when operation/stoppage of thecompressor is switched, according to this motion of the compressor,opening/closing of the expansion valve needs to be controlled. As amethod of controlling the valve, for example, in the Patent document 3is disclosed a technique that at the stoppage of the compressor iscontrolled the motor-driven expansion valve so as to be fully-closedonce, and a predetermined period of time later, the valve isfully-opened to uniform gas pressure in a refrigeration cycle, and whenstarting the operation of the compressor, the valve opening of the valveis set to be an initial opening (preliminarily set standard opening) ora memorized opening (the valve opening just before the compressorstops).

The technique disclosed in the Patent document 3 is applied to airconditioners for adjusting room temperature, so that the gas pressure inthe cycle is uniformed in the fully-opened state, on the contrary, inrefrigeration and cold storage show cases, to avoid increasing theinside temperature, the uniformity of the gas pressure at the stoppageof the compressor is not carried out in general. For this reason, incase that the technique described above is applied to the control of therefrigeration and cold storage show cases, when the compressor isstopped, the valve opening of the motor-driven expansion valve iscontrolled to be the fully-closed state, and the valve opening is set tobe the initial opening or the memorized opening when starting theoperation of the compressor.

However, as described above, in case that the valve opening of themotor-driven expansion valve is switched between the fully-closedopening and the initial opening (or the memorized opening) in accordancewith the operation/stoppage of the compressor, in each switchingoperation/stoppage of the compressor, the valve opening of the valve isto be changed with great operation amount.

In addition, in the refrigeration and cold storage show cases, thenumber of switching of the operation/stoppage of the compressor iscomparatively large, there are quite a few case that is required a heavyswitching action repeating operation/stoppage at five minute intervals.In such a case, the number of switching operation/stoppage of thecompressor is more than ten times an hour, resulting in seriouslyincreased driving frequency of the motor-driven expansion valve.

Further, the motor-driven expansion valve is a machine component withsliding parts, so that as the driving frequency increases, abrasion ofthe sliding parts advances to shorten the life of the valve, and itsdurability life is generally defined in terms of the number of thedriving pulses added to the pulse motor. For this reason, when thenumber of driving pulses added to the pulse motor is considerablyincreased by changing the valve opening as described above, remainingnumber of pulses defined as the durability life are rapidly consumed,resulting in shortened life of the motor-driven expansion valve. As aresult, frequent replacements of the motor-driven expansion valve areforced to be carried out, consequently, generating a problem ofdecreased reliability of the refrigeration and cold storage show cases.

Patent document 1: Japanese Patent Publication No. Heisei 11-230624gazette

Patent document 2: Japanese Patent No. 3936345 gazette

Patent document 3: Japanese Examined Utility Model Publication (Kokoku)No. Heisei 2-3093 gazette

BRIEF SUMMARY OF THE INVENTION

The present invention has been made in consideration of the problems,and the object thereof is to provide a valve controller and otherscapable of improving reliability of refrigeration systems andlengthening life of the systems.

In detail, the object of the present invention is to appropriatelycontrol valve opening of a motor-driven valve and to prevent damage of acontrolled object for its temperature when an abnormality occurs in atemperature sensor, a pressure sensor or the like, and also the objectis to appropriately modify a difference in the valve opening of themotor-driven valve caused by a catching of a foreign substance or thelike and to prevent a trouble such as refrigerant leakage. Further, theobject of the present invention is to prevent the number of drivingpulses of a driving signal for driving a motor-driven valve fromexcessively increasing under a condition that operation/stoppage of acompressor is frequently switched to lengthen the life of themotor-driven valve, consequently, to improve reliability of therefrigeration and cold storage system itself.

To achieve the above object, the present invention relates to a valvecontroller for detecting one of temperature and pressure of arefrigeration cycle based on an output value of a sensor and controllingvalve opening of a motor-driven valve based on a detected value, and thevalve controller is characterized by comprising: valve opening settingmeans for performing one of setting and changing an emergency valveopening of the motor-driven valve; and valve opening controlling meansfor stopping, when an abnormality occurs in the sensor, movement of themotor-driven valve at an emergency valve opening to which one of thesetting and the changing is performed through the valve opening settingmeans.

With the valve controller of the present invention, when an abnormalityoccurs in the sensor the motor-driven valve is stopped at the set orchanged emergency valve opening, so that setting an intermediate valveopening, as the emergency valve opening, between the valve openings inthe fully-opened and the fully-closed states, as an example, preventsthe refrigeration cycle from unintentionally stopping. As a result, evenwhen a prompt repair work cannot be conducted it becomes possible toprevent the object to be managed for its temperature from being damaged.In addition, the emergency valve opening can freely be set or changed,which allows the emergency valve opening to suitably be set inaccordance with usage of the refrigeration cycle and user's request,resulting in a refrigeration cycle with improved flexibility andconvenience.

In the valve controller as described above, the emergency valve openingcan be larger than a valve opening in a fully-closed state and smallerthan a valve opening in a fully-opened state, and may be a valve openingcapable of continuing operation of the refrigeration cycle.

In the above valve controller, the sensor may be one of a temperaturesensor for detecting temperature of a controlled object and a pressuresensor for detecting pressure of a refrigerant circulating in therefrigeration cycle.

It is possible that the valve controller described above furthercomprises communication means for performing one of setting and changingthe emergency valve opening from an outer device by utilizing one ofwire communication and wireless communication.

Further, in the above valve controller, the motor-driven valve may beone of an expansion valve in the refrigeration cycle and a flow controlvalve in a hot gas bypass circuit of the refrigeration cycle.

Still further, the present invention relates to a valve controller forcontrolling valve opening of a motor-driven valve and initializationprocessing of the motor-driven valve, the valve controller ischaracterized by comprising: valve opening controlling means forcontrolling valve opening of the motor-driven valve; initialization timesetting means for setting initialization time that determines intervalsfor performing the initialization processing of the motor-driven valve;time measuring means for measuring elapsed time; and initializationcontrolling means for performing the initialization processing of themotor-driven valve when elapsed time that is measured by the timemeasuring means reaches to the initialization time and the valve openingcontrolling means stops valve opening control of the motor-driven valveas well.

With the valve controller of the present invention, the initializationtime can be set, and each time the elapsed time that is measured by thetime measuring means reaches to the initialization time, theinitialization processing of the motor-driven valve is performed, sothat not only at the power-up but after that, the initializationprocessing can periodically be carried out. As a result, even when adifference in valve opening caused by catching of a foreign substance orthe like is generated, the difference can periodically be modified,which allows the valve opening of the motor-driven valve to accuratelybe controlled.

In addition to the above, the initialization processing is performedonly at the stoppage of the valve opening control of the motor-drivenvalve, so that the initialization processing can be performed withoutharmful effect to the valve opening control of the motor-driven valve.As a result, it is unnecessary to stop the operation of devices for theinitialization processing, which allows hindrance to the operation ofdevices to be avoided and complexity accompanying the operation to beeliminated as well.

In the above valve controller, it is possible that the valve openingcontrolling means calculates a deviation between a detected temperatureof an object to be adjusted for its temperature and a targettemperature; calculates a target valve opening based on the deviation;and controls valve opening of the motor-driven valve so as to be thetarget valve opening.

In the valve controller described above, the motor-driven valve can be amotor-driven expansion valve in a refrigeration cycle, and the detectedtemperature may be a degree of superheat.

In the valve controller, it is possible that in the refrigeration cycleare connected a compressor, a condenser, a motor-driven valve and anevaporator in this order, and operation/stoppage of the compressor isswitched in accordance with a temperature of a controlled object, andthe initialization controlling means performs the initializationprocessing of the motor-driven valve when elapsed time that is measuredby the time measuring means reaches to the initialization time and thecompressor stops as well.

Further, in the valve controller, it is possible that the refrigerationcycle is provided with a solenoid-operated valve disposed between thecondenser and the evaporator to open/close a refrigerant flow passagebetween them, and the valve controller is provided withsolenoid-operated valve controlling means for closing thesolenoid-operated valve when operation of the compressor stops and foropening the solenoid-operated valve when operation of the compressor isrestarted, and the initialization controlling means performsinitialization processing of the motor-driven valve when elapsed timethat is measured by the time measuring means reaches to theinitialization time and the solenoid-operated valve is closed as well.

In the valve controller, when the solenoid-operated valve is closed thevalve opening controlling means may maintain a valve opening of themotor-driven valve at an opening when operation of the compressor stops,and when the solenoid-operated valve is opened the valve openingcontrolling means can start valve opening control of the motor-drivenvalve from the opening at the stoppage of the compressor. With this, theoperation amount of the motor-driven valve accompanying switching ofoperation/stoppage of the compressor can be small, which makes itpossible to lengthen the life of the motor-driven valve.

Further, the valve controller described above may further comprisescommunication means for setting the initialization time from an outerdevice by utilizing one of wire communication and wirelesscommunication.

Still further, the present invention relates to a valve controllingmethod of controlling valve opening of a motor-driven valve as well asinitialization processing of the motor-driven valve, and the method ischaracterized by comprising the steps of: measuring elapsed time andjudging whether or not the measured elapsed time reaches to aninitialization time that determines intervals for performing theinitialization processing of the motor-driven valve; and performing theinitialization processing of the motor-driven valve when the measuredelapsed time reaches to the initialization time, and valve openingcontrol of the motor-driven valve stops as well.

Further, the present invention relates to a refrigeration and coldstorage system, in which a compressor, a condenser, a motor-drivenexpansion valve and an evaporator are connected in this order, therefrigeration and cold storage system switching operation/stoppage ofthe compressor in accordance with a temperature of a controlled object,further comprising a solenoid-operated valve disposed between thecondenser and the evaporator to open/close a refrigerant flow passagebetween them, wherein when operation of the compressor is stopped thesolenoid-operated valve is closed and a valve opening of themotor-driven expansion valve is maintained at an opening when theoperation of the compressor stops, and when the operation of thecompressor is restarted the solenoid-operated valve is opened and valveopening control of the motor-driven expansion valve starts from theopening at the stoppage of the compressor.

With the refrigeration and cold storage system of the present invention,the solenoid-operated valve is disposed between the condenser and theevaporator, and when operation of the compressor is stopped thesolenoid-operated valve is closed and the valve opening of themotor-driven expansion valve is maintained at the opening when theoperation of the compressor stops, and when the operation of thecompressor is restarted the solenoid-operated valve is opened and thevalve opening control of the motor-driven expansion valve starts fromthe opening at the stoppage of the compressor, which makes it possiblethat operations for fully-closing the motor-driven expansion valve atthe stoppage of the compressor and opening the motor-driven expansionvalve at the start of the compressor are unnecessary while preventinginside temperature at the stoppage of the compressor from increasing. Asa result, it becomes unnecessary to largely change the valve opening ofthe motor-driven expansion valve each time the operation/stoppage of thecompressor is switched, which remarkably reduces the consumption of thenumber of driving pulses. This allows the life of the motor-drivenexpansion valve to be lengthened, consequently, the reliability of therefrigeration and cold storage system to be improved.

Further, the present invention relates to a controller for controllingmotion of a refrigeration and cold storage system, the refrigeration andcold storage system having a refrigeration cycle in which a compressor,a condenser, a motor-driven expansion valve and an evaporator areconnected in this order and a solenoid-operated valve disposed betweenthe condenser and the evaporator to open/close a refrigerant flowpassage between them, the refrigeration and cold storage systemswitching operation/stoppage of the compressor in accordance with atemperature of a controlled object, wherein the controller, whenstopping the operation of the compressor, closes the solenoid-operatedvalve and maintains valve opening of the motor-driven expansion valve atan opening when the operation of the compressor stops, and whenrestarting the operation of the compressor, opens the solenoid-operatedvalve and starts valve opening control of the motor-driven expansionvalve from the opening at the stoppage of the compressor.

With the present invention, in the same manner as the above inventions,even when the operation/stoppage of the compressor is frequentlyswitched, it is possible to prevent the number of driving pulses of thedriving signal for driving the motor-driven expansion valve frombecoming considerably large, which lengthens the life of the valve,consequently, improves the reliability of the refrigeration and coldstorage system itself.

The controller of the refrigeration and cold storage system may furthercomprises: a first control section for switching operation/stoppage ofthe compressor in accordance with the temperature of the controlledobject and controlling opening/closing of the solenoid-operated valve;and a second control section for controlling valve opening of themotor-driven expansion valve in accordance with a degree of superheat ofa refrigerant flowing the evaporator, wherein the second control sectionmonitors opened/closed state of the solenoid-operated valve and stopsoutputting a driving signal for the valve opening control in accordancewith the closing of the solenoid-operated valve.

In the controller of the refrigeration and cold storage system, thefirst control section operates the compressor when the temperature ofthe controlled object is higher or equal to a first setting value thatis set at a predetermined temperature, and the first control sectionstops operation of the compressor when the temperature of the controlledobject is lower or equal to a second setting value that is lower thanthe first setting value.

In the controller of the refrigeration and cold storage system, therefrigeration and cold storage system is used for a refrigeration andcold storage showcase for foods, and the temperature of controlledobject is an inside temperature of the refrigeration and cold storageshowcase.

Further, the present invention relates to a method of controlling motionof a refrigeration and cold storage system, the refrigeration and coldstorage system having a refrigeration cycle in which a compressor, acondenser, a motor-driven expansion valve and an evaporator areconnected in this order and a solenoid-operated valve disposed betweenthe condenser and the evaporator to open/close a refrigerant flowpassage between them, the refrigeration and cold storage systemswitching operation/stoppage of the compressor in accordance with atemperature of a controlled object, wherein the method comprising thesteps of: when stopping the operation of the compressor, closing thesolenoid-operated valve and maintaining a valve opening of themotor-driven expansion valve at an opening when the operation of thecompressor stops; and when restarting the operation of the compressor,opening the solenoid-operated valve and starting valve opening controlof the motor-driven expansion valve from the opening when the operationof the compressor is stopped.

As described above, with the present invention, it becomes possible toprovide a valve controller and others capable of improving reliabilityof refrigeration systems and lengthening life of the systems.

In detail, it is possible to appropriately control valve opening of amotor-driven valve and to prevent damage of a controlled object for itstemperature when abnormality occurs in a temperature sensor, a pressuresensor or the like, and also it is possible to appropriately modify adifference in the valve opening of the motor-driven valve caused by acatching of a foreign substance or the like and to prevent a troublesuch as refrigerant leakage. Further, it is possible to prevent thenumber of driving pulses of a driving signal for driving a motor-drivenvalve from excessively increasing under a condition thatoperation/stoppage of a compressor is frequently switched to lengthenthe life of the motor-driven valve, consequently, to improve reliabilityof the refrigeration and cold storage system itself.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be more apparent from the ensuringdescription with reference to the drawings, wherein:

FIG. 1 is a drawing showing the construction of an example of arefrigeration cycle system with a valve controller according to thefirst embodiment of the present invention;

FIG. 2 is a block diagram showing a degree-of-superheat controller shownin FIG. 1 and peripheral circuits around the controller in detail;

FIG. 3 is a flow chart for explaining interrupt processing of atemperature controller;

FIG. 4 is a flow chart for explaining interrupt processing of thedegree-of-superheat controller;

FIG. 5 is an appearance diagram showing surface of a main body of thedegree-of-superheat controller;

FIG. 6 is a flow chart for explaining operations of inputting andchanging a setting value;

FIG. 7 is a drawing showing the construction of an example of arefrigeration cycle system with a valve controller according to thesecond embodiment of the present invention;

FIG. 8 is a block diagram showing a degree-of-superheat controller shownin FIG. 7 and peripheral circuits around the controller in detail;

FIG. 9 is a flow chart for explaining a managing procession ofinitialization timing;

FIG. 10 is a flow chart for explaining interrupt processing of thedegree-of-superheat controller;

FIG. 11 is a timing diagram showing an example of the operation of therefrigeration cycle system under control shown in FIGS. 3, 9 and 10;

FIG. 12 is a drawing showing the construction of a refrigeration andcold storage system according to the third embodiment of the presentinvention;

FIG. 13 is a flow chart for explaining control operation of adegree-of-superheat controller shown in FIG. 12; and

FIG. 14 is a timing diagram showing an example of operations of asolenoid-operated valve and a motor-driven valve when operation/stoppageof a compressor is switched.

DETAILED DESCRIPTION OF THE INVENTION

A valve controller according to the first embodiment of the presentinvention will be explained with reference to FIGS. 1 to 6. Here, as arefrigeration cycle system is exemplified a system for controllingtemperature inside a refrigeration and cold storage showcase used forcold reserving and displaying foods, in addition, the valve controllerof the present invention is exemplarily used for a device forcontrolling an expansion valve (motor-driven valve) disposed in theabove refrigeration cycle system.

FIG. 1 shows the refrigeration cycle system with the valve controlleraccording to the present invention, and the system 1 is provided with acompressor 2, a condenser 3, a condenser fan 3 a, a solenoid-operatedvalve 4, a motor-driven valve 5, an evaporator 6, an evaporator fan 6 a,an inlet temperature sensor 7, an outlet temperature sensor 8, an insidetemperature sensor 9, a temperature controller 10 and adegree-of-superheat controller 11.

The compressor 2, the condenser 3, the solenoid-operated valve 4, themotor-driven valve 5 and the evaporator 6 are connected with each otherthrough a conduit 12, and among them circulates a refrigerant. Here, thequantity of the refrigerant flowing through the conduit 12 is controlledby adjusting valve opening of the motor-driven valve 5.

The compressor 2 compresses the refrigerant in low pressure gas statefed from the evaporator 6 and changes it into high pressure gas state soas to be fed to the condenser 3 through the conduit 12.

The condenser 3 condenses the refrigerant in high pressure gas state fedfrom the compressor 2 to change it into a refrigerant in high pressureliquid state with condensation heat being removed, and the condenser 3releases the removed heat to outside through air blow by the condenserfan 3 a.

The solenoid-operated valve 4 is installed to open/close a refrigerantflow passage 12 a between the condenser 3 and the evaporator 6 and tochange flow/non-flow of the refrigerant into the evaporator 6. Thissolenoid-operated valve 4 operates depending on a solenoid-operatedvalve driving signal SV outputted from the temperature controller 10,and the valve 4 opens/closes in accordance with a voltage level of thesolenoid-operated valve driving signal SV.

The motor-driven valve 5 changes the refrigerant in high pressure liquidstate fed from the condenser 3 into low pressure state. This valve 5 isprovided with a built-in pulse motor 5 a (shown in FIG. 2) that isdriven in accordance with a motor-driven valve driving signal EV fromthe degree-of-superheat controller 11, and the valve opening of thevalve 5 is adjusted by the rotation of the pulse motor 5 a withrotational angles in accordance with the number of pulses of themotor-driven valve driving signal EV.

The evaporator 6 is provided to evaporate (vaporize) the refrigerant inlow pressure liquid state, and the refrigerant removes evaporation heatfrom its circumference through the evaporation, and is heated. At thismoment, the removed heat cools ambient air around the evaporator 6, andthe cooled air is released by the air blow by the evaporator fan 6 a toadjust temperature inside the refrigeration and cold storage show case.

The inlet temperature sensor 7, the outlet temperature sensor 8 and theinside temperature sensor 9 detect a temperature Tin of the refrigerantat the inlet of the evaporator 6 (the refrigerant in liquid state), atemperature Tout of the refrigerant at the outlet of the evaporator 6(the refrigerant in gas state) and a temperature Tis inside therefrigeration and cold storage show case respectively. These sensors 7to 9 are constructed by thermistors with negative temperature-resistancecharacteristic for instance.

The temperature controller 10 is a control circuit for adjustingtemperature inside the refrigeration and cold storage show case bycontrolling operation/stoppage of the compressor 2, and is constructed,for example, by a microcomputer and peripheral circuits (both of themare not shown). The temperature controller 10 compares the insidetemperature Tis detected by the inside temperature sensor 9 and apreliminarily set temperature Ton for turning on the compressor 2(hereinafter called as “ON set temperature”), and a preliminarily settemperature Toff for turning off the compressor 2 (hereinafter called as“OFF set temperature”) with each other, and in accordance with theresults, controls the operation/stoppage of the compressor 2. And,between the ON set temperature Ton and the OFF set temperature Toff isset a “DIFFERENTIAL (difference in temperature)” to avoid frequentoperation/stoppage actions (hunting) of the compressor 2.

In addition, the temperature controller 10 has a function of controllingopening/closing of the solenoid-operated valve 4 in accordance with anoperating condition of the compressor 2 also, and the opening/closingcontrol of the valve 4 is performed through the solenoid-operated valvedriving signal SV. This solenoid-operated valve driving signal SV is setat a voltage level (for example AC 200V) for opening thesolenoid-operated valve 4 while the compressor 2 is in operation, on theother hand, the signal SV is set at a voltage level (for example 0V) forclosing the solenoid-operated valve 4 while the compressor 2 is instoppage.

The degree-of-superheat controller 11 is a control circuit forcontrolling valve opening of the motor-driven valve 5, and isconstructed, for example, by a microcomputer and peripheral circuits inthe same manner as the temperature controller 10. This controller 11calculates valve opening of the motor-driven valve 5 through a PIDcontrol based on a degree of superheat Tsh of the refrigerant in theevaporator 6 (the temperature Tout detected by the outlet temperaturesensor 8−the temperature Tin detected by the inlet temperature sensor7), and outputs the motor-driven valve driving signal EV correspondingto the calculated valve opening to the pulse motor 5 a of themotor-driven valve 5.

In addition, the degree-of-superheat controller 11 has a function ofmonitoring abnormality in the inlet temperature sensor 7 and the outlettemperature sensor 8 also, in case that outputs of these temperaturesensor 7, 8 are abnormal, the controller 11 changes the valve opening ofthe motor-driven valve 5 to a preliminarily set emergency valve openingSP. Further, as will hereinafter be described in detail, the emergencyvalve opening SP can be set any value by one pulse by users.

The degree-of-superheat controller 11 is, as shown in FIG. 2, providedwith a micro processor 13, an inlet temperature detecting circuit 14, anoutlet temperature detecting circuit 15, a motor-driven valve drivingcircuit 16, an input circuit 17, a display circuit 18, a display drivercircuit 19, a memory circuit (EEPROM) 20, a control signal input circuit21 and a communication signal conversion circuit 22.

The inlet temperature detecting circuit 14 is a resistance-voltageconversion circuit that converts a resistance value of the inlettemperature sensor 7 to a DC-voltage signal and outputs it to the microprocessor 13. This inlet temperature detecting circuit 14 provides anelectric signal (inlet temperature signal) corresponding to thetemperature Tin of the refrigerant at the inlet of the evaporator 6 tothe micro processor 13.

The outlet temperature detecting circuit 15 is a resistance-voltageconversion circuit that converts a resistance value of the outlettemperature sensor 8 to a DC-voltage signal and outputs it to the microprocessor 13. This outlet temperature detecting circuit 15 provides anelectric signal (outlet temperature signal) corresponding to thetemperature Tout of the refrigerant at the outlet of the evaporator 6 tothe micro processor 13.

The input circuit 17 is disposed to input a set degree of superheat(target temperature) Ts, upper and lower opening limits of themotor-driven valve 5 (for instance, when the motor-driven valve 5 isused with 100 pulses to 400 pulses, the upper opening limit is set to be400 pulses and the lower opening limit to be 100 pulses), eachcoefficient for P (proportional), I (integral) and D (differential) at aPID control, the emergency valve opening SP and so on. These varietiesof input values can be set as setting values, and the setting values setcan be changed with the input circuit 17 also. Methods of setting theinput value and changing the setting value will be explained below indetail.

This input circuit 17 is provided with four tact switches 17 a to 17 d(an up switch 17 a, a down switch 17 b, a set switch 17 c and an enterswitch 17 d), and ON/OFF states of the tact switches 17 a to 17 d areoutputted to the micro processor 13.

The display circuit 18 is provided with a temperature displaying element18 a, a valve opening displaying element 18 b and a plurality of LEDs 18c. The temperature displaying element 18 a displays the refrigeranttemperature Tin at the inlet and the refrigerant temperature Tout at theoutlet of the evaporator 6, and the degree of superheat Tsh (=Tout−Tin)while switching them, and in a setting mode, setting values of the setdegree of superheat Ts, the upper opening limit, the lower openinglimit, the emergency valve opening SP and others are displayed. Inaddition, the valve opening displaying element 18 b displays the presentvalve opening of the motor-driven valve 5 by the number of pulses fromthe fully-closed state.

The plurality of LEDs 18 c turn on in relation to displayed items of thetemperature displaying element 18 a and the valve opening displayingelement 18 b, and consist of six LEDs from “degree of superheat” to“alarm”. Each LED for “degree of superheat”, “inlet” and “outlet” showsa displayed item of the temperature displaying element 18 a and turns onin relation to the temperature displayed on the temperature displayingelement 18 a. Further, the LED for “setting” turns on when thedegree-of-superheat controller 11 is in a setting mode, and the LED for“drive” turns on when the controller 11 is in operation. The LED for“alarm” turns on when an output data of the inlet temperature sensor 7or the outlet temperature sensor 8 is abnormal.

The display driver circuit 19 amplifies a signal from the microprocessor 13 and outputs the amplified signal to the display circuit 18.The memory circuit 20 stores the above setting values and so on forbacking up.

The motor-driven valve driving circuit 16 is disposed to amplify adriving control signal from the micro processor 13 and to output drivingpulses to the pulse motor (stepping motor) 5 a built in the motor-drivenvalve 5, and is provided with a driver IC (integrated circuit) (drivingsignal amplifying circuit) 16 a, etc.

The micro processor 13 is provided with an A/D converter 13 a, a CPU(Central Processing Unit) 13 b, a ROM 13 c, a RAM 13 d, a timer 13 e, anI/O (13 f) and so on.

The A/D converter 13 a converts analog signals on temperature outputtedfrom the inlet temperature detecting circuit 14 and the outlettemperature detecting circuit 15 into digital signals, and the CPU 13 binterprets and executes programs stored in the ROM 13 c. The ROM 13 c isa nonvolatile memory storing an operation program for executing valveopening control by PID control operation described below, a program forcontrolling valve opening of the motor-driven valve 5 when anabnormality occurs in the temperature sensors 7,8, a display controlprogram and so on. The RAM 13 d functions as a work memory of the CPU 13b. The timer 13 e is provided to perform interrupt processing and so on,and the I/O (13 f) is provided to exchange data between the CPU 13 b andother devices.

The control signal input circuit 21 converts the solenoid-operated valvedriving signal SV (alternating current voltage signal: 200V-0V)outputted from the temperature controller 10 into a binary signal of DCvoltage (DC5V-0V) and outputs the binary signal to the micro processor13 as a signal indicating opened/closed state of the solenoid-operatedvalve 4.

The communication signal conversion circuit 22 is an interface circuitto connect an external device such as personal computer (PC) 23 to themicro processor 13 via a connection cable 23 a or the like, and isdisposed to input various setting values such as the set degree ofsuperheat Ts, the emergency valve opening SP and the others from theoperation of the PC 23. This circuit 22 performs mutual conversion ofsignal's voltage level, the number of input and output terminals and thelike in accordance with differences between a signal format on the sideof the micro processor 13 and that on the side of the PC 23, forinstance, and the circuit 22 is composed of a RS-232C transceiver IC,etc.

Next, the operation of the refrigeration cycle system 1 with theconstruction described above will be explained. Here, at first, theinterrupt processing performed by the temperature controller 10 will beexplained with reference to FIGS. 1, 3. During the operation of thesystem, the temperature controller 10 carries out a routine shown inFIG. 3 while using a timer (not shown) or the like at predeterminedintervals (every ten seconds, as an example).

When the interrupt processing is started, the temperature controller 10,as shown in FIG. 3, takes in the inside temperature Tis detected by theinside temperature sensor 9 (Step S1), and judges whether or not theinside temperature Tis is higher or equal to the ON set temperature Ton(Step S2). At this time, for instance, in case that the insidetemperature Tis tends to increase and the inside temperature Tis ishigher or equal to the ON set temperature Ton (Step S2: Yes), thecompressor 2 is started (Step S3). At the same time, thesolenoid-operated valve 4 is opened to open the refrigerant flow passage12 a between the condenser 3 and the evaporator 6 (Step S4). This allowsthe evaporator fan 6 a to discharge a cold blast, which cools inside therefrigeration and cold storage show case and decreases the insidetemperature Tis.

After that, when the inside temperature Tis gradually decreases and theinside temperature Tis detected by the inside temperature sensor 9becomes lower than the ON set temperature Ton (Step S2: No), thetemperature controller 10 judges whether or not the inside temperatureTis is lower or equal to the OFF set temperature Toff (Step S5). As aresult, in case that the inside temperature Tis is higher than the OFFset temperature Toff (Step S5: No), operation state (driving condition)of the compressor 2 at the time is maintained to sequentially decreasethe inside temperature Tis. At this time, in the solenoid-operated valve4 also, opened/closed state of the valve 4 at the time (opened state) ismaintained to sequentially open the refrigerant flow passage 12 a.

Then, when the inside temperature Tis is sufficiently decreased and theinside temperature Tis detected by the inside temperature sensor 9becomes lower or equal to the OFF set temperature Toff (Step S5: Yes),the operation of the compressor 2 is stopped, and the solenoid-operatedvalve 4 is closed to close the refrigerant flow passage 12 a as well(Steps S8, S9). This stops cooling operation of the refrigeration andcold storage show case and slowly increases the inside temperature Tis.

Afterward, the operations from Steps S1 to S9 described above arerepeated at ten second intervals, and when the inside temperature Tisbecomes higher or equal to the ON set temperature Ton again, operatingthe compressor 2 and opening the solenoid-operated valve 4 are restartedto decrease the inside temperature Tis.

Next, control operation performed by the degree-of-superheat controller11, particularly, operation of the micro processor 13 constituting amain part of the degree-of-superheat controller 11 will be explainedwith reference to FIGS. 1, 2 and 4. In addition, this procession isperformed at ten second intervals also, for instance, in the same manneras the control operation of the temperature controller 10 shown in FIG.3.

When the interrupt processing is started, as shown in FIG. 4, the microprocessor 13 of the degree-of-superheat controller 11 takes in therefrigerant temperature Tin at the inlet of the evaporator 6 (Step S11),and the degree-of-superheat controller 11 judges whether or not a valuedetected by the inlet temperature sensor 7 is abnormally hightemperature (for example exceeding 60°) (Step S12). This judgmentprocessing is performed to detect a short-circuit fault of the inlettemperature sensor 7, in a thermistor, as an ambient temperatureincreases, a resistance value thereof decreases, so that judging whetheror not the detected inlet temperature Tin is abnormally high is able toconfirm whether or not the resistance value of the inlet temperaturesensor 7 is extremely low.

As a result of the judgment, when the inlet temperature Tin exceeds 60°(Step S12: Yes) there is a fear that a short-circuit fault occurs in theinlet temperature sensor 7, so that to the motor-driven valve 5 isoutputted the motor-driven valve driving signal EV to shift the valveopening of the motor-driven valve 5 to the emergency valve opening SP,and then, the valve 5 is stopped at the emergency valve opening SP (StepS13).

Here, as described above, although the emergency valve opening SP canarbitrarily be set with the input circuit 17, the PC 23 and the othersby users, in case that stoppage of cooling operation caused by thefully-closed or the fully-opened states of the motor-driven valve 5should be avoided to precede conservation of foods preserved inside, asthe emergency valve opening SP, it is preferable to set it as anintermediate value (for instance 100 to 200 pulse) between thefully-opened value and the fully-closed value. This can prevent stoppageof circulating refrigerant and liquid back, which is generated whenextremely large amount of refrigerant is supplied to the evaporator 6,which allows the refrigeration cycle system 1 to continuously beoperated under the condition that a certain cooling capacity isprovided.

In this connection, for instance, in case that the refrigeration cyclesystem 1 is operated using a stand-by sensor under the condition that atemperature sensor can rapidly be repaired or replaced, as the emergencyvalve opening SP, it is preferable that the valve opening of themotor-driven valve 5 is set to be the fully-closed or the fully-openedvalue. With this, the operation of the refrigeration cycle system 1 canbe stopped immediately in the stage that an abnormality occurs in thetemperature sensor and the abnormality can instantaneously be informed.

On the other hand, when the inlet temperature Tin is below 60° (StepS12: No), the micro processor 13 judges whether or not the inlettemperature Tin is abnormally low (for instance below −60° (Step S14).This judgment processing is performed to detect an open-circuit fault ofthe inlet temperature sensor 7, and judging whether or not the detectedinlet temperature Tin is abnormally low is able to confirm whether ornot the resistance value of the inlet temperature sensor 7 is extremelyhigh.

As a result of the judgment, in case that the inlet temperature Tin islower than −60° (Step S14: Yes), in the same manner as described above,the motor-driven valve 5 is stopped at the emergency valve opening SP,in accordance with usage of the refrigeration cycle system 1, and foodsinside the case is preserved and the inlet temperature sensor 7 ispromoted to be repaired or replaced (Step S13).

On the other hand, in case that the inlet temperature Tin is higher orequal to −60° (Step S14: No), no abnormality is found in the inlettemperature sensor 7, so that the refrigerant temperature Tout at theoutlet of the evaporator 6 is taken in (Step S15). Then, in the samemanner as the inlet temperature sensor 7, the micro processor 13 judgeswhether or not a value detected by the outlet temperature sensor 8 isabnormally high and whether or not it is abnormally low (Steps S16,S17). As the results of the judgments, when an abnormality is found inthe outlet temperature sensor 8, the valve opening of the motor-drivenvalve 5 is shifted to the emergency valve opening SP, and the valve 5 isstopped at the emergency valve opening SP (Step S13).

On the contrary, when no abnormality is found in the outlet temperaturesensor 8, a normal control operation of the valve opening is started;the present degree of superheat Tsh (=Tout−Tin) is calculated; and adeviation e(t) (=Ts−Tsh) between a set degree of superheat (target valueof the degree of superheat Tsh) and the present degree of superheat iscalculated (Steps S18, S19) as well. Next, based on a set of thedeviation e in the past, the proportional band PB, the integration timeTi and the derivative time Td, the operation amount m(t) of the valveopening at this time is calculated with a PID (proportional, integraland differential) calculation in accordance with the following formula 1(Step S20). Here, Kp is a proportional gain.

M(t)=K _(p) {e(t)+1/T _(i) ∫e(t)dt+T _(d) de(t)/dt}  [Formula 1]

-   -   where, K_(p)=100/PB

Then, the target valve opening of the motor-driven valve 5 is calculatedbased on the calculated operation amount m(t) (Step S21), and thedegree-of-superheat controller 11 sets the number of driving pulses suchthat the valve opening of the motor-driven valve 5 becomes the targetvalve opening, and outputs the motor-driven valve driving signal EV tothe motor-driven valve 5 to increase/decrease the valve opening of thevalve 5 (Step S22).

Next, the whole stream of inputting (changing) operation of each settingvalue with the input circuit 17 and the display circuit 18 shown in FIG.2 will be explained with reference to FIG. 5 and Table 1. Meanwhile,FIG. 5 is an appearance diagram showing surface of a main body of thedegree-of-superheat controller 11.

For instance, under the condition that a temperature and the presentvalve opening are respectively displayed on the temperature displayingelement 18 a and the valve opening displaying element 18 b, depressingthe set switch 17 c enters the setting mode, and the temperaturedisplaying element 18 a shifts from a temperature display mode to asetting value display mode, and the valve opening displaying element 18b switches display from the present valve opening to a setting item.

The setting value (numerical number) displayed on the temperaturedisplaying element 18 a can be increased/decreased by depressing the upswitch 17 a or the down switch 17 b, and depressing the enter switch 17d allows the displayed setting value to be renewed and stored as a newsetting value.

On the other hand, the setting items are, for example as shown in Table1, nine in number, and on the valve opening displaying element 18 b isdisplayed a setting value number and a symbol, for instance, “1. HV”.This setting item is, in the setting mode, by depressing the set switch17 c, sequentially switched to the next one, and when the setting item 9(“8. SP”) is displayed, depressing the set switch 17 c quits the settingmode and returns to the condition that temperature and valve opening aredisplayed.

TABLE 1 MINIMUM MAXIMUM No. SIGNAL SETTING ITEM VALUE VALUE UNIT 0. SHDEGREE OF SUPERHEAT 1 30 ° C. 1. HV UPPER LIMIT OPENING 1 500 pulse 2.LV LOWER LIMIT OPENING 0 499 pulse 3. P P 1 100 % 4. i I 1 5000 second5. d D 0 5000 second 6. SV STARTING OPENING 0 500 pulse 7. St. STARTINGTIME 0 1200 second 8. SP EMERGENCY VALVE OPENING 0 500 pulse

Meanwhile, various setting values shown in the Table. 1, as describedabove, can be set and changed by operations from the PC 23 utilizingcommunication also.

Next, inputting (changing) operation of each setting value with theinput circuit 17 and the display circuit 18 will be explained withreference to FIGS. 5, 6.

When displaying a temperature on the temperature displaying element 18 a(Step S31), in Step S32, whether or not the set switch 17 c is depressedis judged, and when depressed, in Step S33, on the temperaturedisplaying element 18 a is displayed a setting value, and on the valveopening displaying element 18 b is displayed a number and a symbolcorresponding to the setting value as well, and it enters the settingmode, when the set switch 17 c is not depressed it returns to thecondition of Step S31.

Next, in Step S34, whether or not the up switch 18 a is depressed isjudged, when depressed, in Step S35, whether or not displayed value onthe temperature displaying element 18 a is the maximum value of thesetting value is judged. As a result of the judgment, when the displayedvalue is not the maximum value of the setting value, in Step S36, thedisplayed value is incremented and it returns to Step S34. On the otherhand, when the displayed value is the maximum value of the settingvalue, it returns to Step S34 as it is.

In Step S34, when the up switch 17 a is judged not to be depressed, inStep S37, whether or not the down switch 17 b is depressed is judged,when depressed, in Step S38, whether or not the displayed value is theminimum value of the setting value is judged, when the displayed valueis not the minimum value of the setting value, in Step S39, thedisplayed value is decremented and it returns to Step S34. On the otherhand, when the displayed value is the minimum value of the setting valueit returns to Step S34 as it is.

In Step S37, when the down switch 17 b is judged not to be depressed, inStep S40, whether or not the enter switch 17 d is depressed is judged,when depressed, in Step S41, the setting value is renewed to the presentdisplayed value, and the renewed setting value is stored in the memorycircuit 20 of FIG. 2, and it returns to Step S34.

When the enter switch 17 d is not depressed in Step S40, in Step S42,whether or not the set switch 17 c is depressed is judged, when judgednot to be depressed, it returns to Step S34.

In Step S42, when the set switch 17 c is judged to be depressed, in StepS43, whether or not the setting is finished is judged. Concretely, inStep S42, under the condition that the setting item 9 “emergency valveopening” is displayed, when the set switch 17 c is depressed the settingmode is judged to be finished in Step S43, and it returns to Step S31.

On the other hand, in Step S42, under the condition that an item otherthan the setting item 9 “emergency valve opening” is selected, when theset switch 17 c is depressed, in Step S44, the next setting value isdisplayed on the temperature displaying element 18 a; a number and asymbol corresponding to the next setting are displayed on the valveopening displaying element 18 b; it returns to Step S34; and the abovemotions are repeated.

The above operations are able to input (change) each setting value, andthe emergency valve opening SP can freely be set also. In addition, theemergency valve opening SP can freely be set also after it was set once,further, the set emergency valve opening SP can be changed not onlyduring the stoppage of the refrigeration cycle system 1 but also duringthe operation of the system 1.

As described above, with the present embodiment, as the emergency valveopening SP of the motor-driven valve 5, intermediate valve openingvalues excluding those in the fully-opened and fully-closed states canbe set, in addition to that, in case that an abnormality occurs in theinlet and outlet temperature sensors 7, 8, the motor-driven valve 5 isstopped at the set emergency valve opening SP, so that even if anabnormality occurs in the sensors 7, 8, stoppage of the refrigerationcycle system 1 due to a low-pressure abnormality and liquid back can beavoided. This can continue cooling operation inside the case until amaintenance worker arrives, which prevents bruised foods even if swiftrepair is impossible.

Further, since the emergency valve opening SP can freely be changed, theemergency valve opening SP can be set in accordance with usage of therefrigeration cycle system 1 and user's request thereto, for instance,besides the control specifying the valve opening to the intermediatevalve opening values, a control intentionally stop the system 1 is alsoselectable. This can increase degree of freedom in selecting motion ofthe motor-driven valve 5, and improve versatility and convenience of therefrigeration cycle system 1.

In addition, in the present embodiment described above, although thecase that an abnormality occurs in the inlet and outlet temperaturesensors 7, 8 is exemplified, the present invention can be applied to asensor detecting a temperature at the valve opening control of themotor-driven valve 5 other than the inlet and outlet temperature sensors7, 8, moreover, the present invention can be applied also when anabnormality occurs in a pressure sensor detecting pressure of therefrigerant circulating in the refrigeration cycle.

Next, a valve controller according to the second embodiment of thepresent invention will be explained with reference to FIGS. 7 to 11. InFIGS. 7, 8, like symbols are applied to like constituents shown in FIGS.1, 2, and detailed explanation thereof will be omitted.

Further, in the present embodiment also, as a refrigeration cycle systemis exemplified a system for controlling temperature inside arefrigeration and cold storage showcase used for cold reserving anddisplaying foods, in addition, the valve controller of the presentinvention is exemplarily used for a device for controlling an electricexpansion valve (motor-driven valve) disposed in the above refrigerationcycle system described above.

FIG. 7 shows the refrigeration cycle system with the valve controlleraccording to the second embodiment, and the system 30 is provided withthe compressor 2, the condenser 3, the condenser fan 3 a, thesolenoid-operated valve 4, the motor-driven valve 5, the evaporator 6,the evaporator fan 6 a, the inlet temperature sensor 7, the outlettemperature sensor 8, the inside temperature sensor 9, the temperaturecontroller 10 and a degree-of-superheat controller 31.

The degree-of-superheat controller 31 is a control circuit forcontrolling valve opening of the motor-driven valve 5, and isconstructed by a microcomputer and peripheral circuits for instance.This controller 31 calculates valve opening of the motor-driven valve 5through PID control based on the degree of superheat Tsh of therefrigerant in the evaporator 6 (Tsh=the temperature Tout detected bythe outlet temperature sensor 8−the temperature Tin detected by theinlet temperature sensor 7), and outputs the motor-driven valve drivingsignal EV corresponding to the calculated valve opening to the pulsemotor of the motor-driven valve 5.

In addition, the degree-of-superheat controller 31 has functions ofdetecting opened/closed states of the solenoid-operated valve 4 bymonitoring a voltage level of the solenoid-operated valve driving signalSV, and switching presence/absence of an output of the motor-drivenvalve driving signal EV to the motor-driven valve 5 in accordance withthe opened/closed states of the solenoid-operated valve 4. Further thecontroller 31 has a function of controlling an initialization processingof the motor-driven valve 5 also, and controls execution timings of theinitialization processing (hereinafter called as “initializationtiming”) in accordance with opening/closing timings of thesolenoid-operated valve 4 and time measured by a timer described below.

Meanwhile, a setting value determining the initialization timing(initialization time It), in the same manner as “the emergency valveopening SP” in the first embodiment, can be inputted with the inputcircuit 17, or inputted by operating the PC 23 through the communicationsignal conversion circuit 22. Further, specific input and changeoperations of the initialization time It are performed in the samemanner as shown in FIGS. 5 and 6.

The degree-of-superheat controller 31 is, as shown in FIG. 8, providedwith the micro processor 13, an inlet temperature detecting circuit 34,an outlet temperature detecting circuit 35, the motor-driven valvedriving circuit 16, the input circuit 17, the display circuit 18, thedisplay driver circuit 19, the memory circuit (EEPROM) 20, the controlsignal input circuit 21 and the communication signal conversion circuit22.

The inlet temperature detecting circuit 34 is a resistance-voltageconversion circuit for converting a resistance value of the inlettemperature sensor 7 to a DC-voltage signal and outputting it to themicro processor 13. In order to accurately detect the temperature Tin ofa refrigerant at the inlet of the evaporator 6, this inlet temperaturedetecting circuit 34 is constructed by a bridge circuit 34 a and anamplifying circuit 34 b for amplifying a voltage between intermediateterminals of the bridge circuit 34 a.

The outlet temperature detecting circuit 35 is a resistance-voltageconversion circuit for converting a resistance value of the outlettemperature sensor 8 to a DC-voltage signal and outputting it to themicro processor 13. This outlet temperature detecting circuit 35 is alsoconstructed by a bridge circuit 35 a and an amplifying circuit 35 b toaccurately detect the temperature Tout of a refrigerant at the outlet ofthe evaporator 6.

Next, the operation of the refrigeration cycle system 30 with theconstruction described above will be explained.

The interrupt processing performed by the temperature controller 10 iscarried out in the same manner as the first embodiment, and the routineshown in the FIG. 3 while using a timer (not shown) and the like isperformed at predetermined intervals (every ten seconds, as an example).

Next, a control operation performed by the degree-of-superheatcontroller 31, particularly, operation of the micro processor 13constituting a main part of the controller 31 will be explained. Here,at first, management processing of the initialization timing will beexplained with reference to FIGS. 7 to 9. Meanwhile, this procession isdifferent from the control operation of the temperature controller 10shown in FIG. 3, and is continuously performed while the refrigerationcycle system 30 is in operation.

As shown in FIG. 9, when power is supplied to start operation of therefrigeration cycle system 30 (Step S51), the micro processor 13 setsthe initialization time It, which is set by the input circuit 17 or thePC 23, to a start value (at a down count) of the timer 13 e (Step S52).

Next, an initialization flag Fi is cleared (set it to “0”) (Step S53),and the down count of the timer 13 e is started as well (Step S54).Here, the initialization flag Fi shows necessity of the initializationprocessing of the motor-driven valve 5, and in case that the value ofthe flag Fi is “1”, the flag Fi shows that the initialization processingshould be carried out, and in case that the value of the flag Fi is “0”,which means the initialization processing is not required.

After that, the down count is continued until the count value of thetimer 13 e reaches to “0” (Step S55), and when the count value reachesto “0” (time up) (Step S55: Yes), the initialization flag Fi is set tobe “1” (Step S56). Then, the initialization time It is set to the startvalue of the timer 13 e again (Step S57), and the down count of thetimer 13 e is started (Step S58).

Hereinafter, until a power source is turned off to stop the operation ofthe refrigeration cycle system 30, the processes in the Steps S55 to S58are repeated (Step S59) to continuously manage the initializationtiming.

Next, an interrupt processing performed by the degree-of-superheatcontroller 31 will be explained with reference to FIGS. 7, 8 and 10.Meanwhile, this procession is carried out in synchronization with thecontrol operation of the temperature controller 10 at ten secondintervals, for instance, in the same manner as the control operation ofthe temperature controller 10 thereof shown in FIG. 3.

When the interrupt processing is started, as shown in FIG. 10, the microprocessor 13 of the degree-of-superheat controller 31 judges whether ornot the solenoid-operated valve 4 is opened with reference toopening/closing signals (a convert signal of the solenoid-operated valvedriving signal SV) outputted from the control signal input circuit 21(Step S61). As a result of the judgment, in case that the valve 4 isopened (Step S61: Yes), the degree-of-superheat controller 31 takes inrefrigerant temperatures Tin, Tout at the inlet and outlet of theevaporator 6 respectively (Steps S62 and S63) to calculate the presentdegree-of-superheat Tsh (=Tout−Tin) (Step S64).

Next, a deviation e(t) (=Ts−Tsh) between a set degree-of-superheat(target value of the degree of superheat Tsh) Ts and the presentdegree-of-superheat Tsh is calculated (Step S65), and based on a set ofthe deviation e in the past, the proportional band PB, the integrationtime Ti and the derivative time Td, the operation amount m(t) of thevalve opening at this time is calculated with a PID (proportional,integral and differential) calculation in accordance with the aboveformula 1 (Step S66).

This calculates a target valve opening that the motor-driven valve 5should reach to, and the degree-of-superheat controller 31 specifies thenumber of driving pulses such that a valve opening of the valve 5becomes the target valve opening, and outputs the motor-driven valvedriving signal EV to the valve 5 to increase/decrease the valve openingof the valve 5 (Step S67).

On the other hand, as a result of the above judgment in Step S61, incase that the solenoid-operated valve 4 is closed (Step S61: No), themicro processor 13 judges whether or not the initialization flag Fi isset to be “1” (Step S68). As the result, in case that the initializationflag Fi is set to be “0” (Step S68: No), any procession is notperformed, and changing the valve opening of the motor-driven valve 5and the like are not carried out.

On the contrary, in case that the initialization flag Fi is set to be“1” (Step S68: Yes), the micro processor 13 judges whether or not thetarget valve opening of the motor-driven valve 5 is set to be a −α pulse(Step S69). Here, “−α pulse” is a valve opening value to allow themotor-driven valve 5 to be driven in a closing direction and to be inthe fully-closed state. Meanwhile, although a valve opening value in thefully-closed state is usually 0 pulse, the target valve opening value isset to be −α pulse (minus value). This is because in view of catching ofa foreign matter or the like, to the valve opening value in thefully-closed state (0 pulse) is added a margin of a few pulses(approximately 8 pulses as an example) in a direction that the valve 5closes (see FIG. 11 (g)). In addition, in the Step S69, the reason whythe micro processor 13 judges whether or not the target valve opening isset to −α pulse is to judge whether or not the initialization processingof the valve 5 has already been started.

In the case described above, for example, when the initializationprocessing of the motor-driven valve 5 has not yet been started, and thetarget valve opening of the valve 5 is set to the valve openingcalculated in the Steps S66, S67 (Step S69: No), it moves to Step S70,and the valve opening Pi of the valve 5 at the time is memorized to theRAM 13 d inside the micro processor 13 as a valve opening Pm just beforethe initialization processing is performed. Next, the target valveopening of the valve 5 is set to −α pulse (Step S71), and theinitialization processing is started (Step S72).

Under the condition, when an interrupt time (ten seconds) passes, themicro processor 13 judges whether or not the target valve opening of themotor-driven valve 5 is set to be −α pulse again (Step S69). At thismoment, since the initialization processing of the motor-driven valve 5has already been started, it moves to Step S73, and the micro processor13 judges whether or not the valve opening Pi of the valve 5 at themoment is set to be −α pulse. Meanwhile, the reason why the judgmentprocessing in Step S73 is performed is to judge whether or not theinitialization processing started in Step S72 is finished.

Then, in case that the valve opening Pi reaches to the −α pulse afterthe initialization processing is finished (Step S73: Yes), the targetvalve opening of the motor-driven valve 5 is set to be the valve openingPm memorized in the RAM 13 d in the previous Step S70 described above(Step S74). Next, the valve 5 is driven (Step S75), and theinitialization flag Fi is set to be “0” (Step S76).

In this connection, when the initialization processing has not yet beenfinished and the valve opening Pi of the motor-driven valve 5 has notreached to −α pulse at the judgment processing in the Step S73 (StepS73: No), the initialization processing is continued (Step S77).

Next, an example of operation of the refrigeration cycle system 30 underthe control shown in FIGS. 3, 9 and 10 will be explained with referenceto FIG. 11. Here, the initialization time It shall be set to be 168hours (24 hours×7(=one week)). In addition, operation of therefrigeration cycle system 30 is started at the time earlier than thetiming t1 shown in FIG. 11, and the clear processing of theinitialization flag Fi and the count start of the timer 13 e at thepower-supply shall have been already started.

As shown in the FIG. 11, in the timing t1, when the inside temperatureTis becomes higher or equal to the ON set temperature Ton, thecompressor 2 is operated and the solenoid-operated valve 4 is opened toopen the refrigerant flow passage 12 a. Further, in response to theopening the solenoid-operated valve 4, the opening/closing signal(control signal) becomes DC-5V, which starts the valve openingadjustment of the motor-driven valve 5 based on a PID calculation so asto adjust flow rate of a refrigerant circulating in the refrigerationcycle. The operation of the compressor 2, the opening of thesolenoid-operated valve 4 and the valve opening adjustment of themotor-driven valve 5 are continuously performed until the insidetemperature Tis is higher than the OFF set temperature Toff even if theinside temperature Tis becomes lower or equal to the ON set temperatureTon.

Then, the temperature inside the refrigeration and cold storage showcase decreases, and in the timing t2, when the inside temperature Tisreaches to the OFF set temperature Toff, the operation of the compressor2 is stopped and the solenoid-operated valve 4 is closed to close therefrigerant flow passage 12 a. In addition, in response to the closingthe solenoid-operated valve 4, the opening/closing signal (controlsignal) becomes 0V, which stops outputting the motor-driven valvedriving signal EV to the motor-driven valve 5 (the number of drivingpulses is set to be zero) and suspends the valve opening adjustment ofthe valve 5. As a result, the valve opening of the motor-driven valve 5remains as that at the stopping of the valve opening adjustment,hereinafter, until the valve opening adjustment is restarted, thecondition is maintained.

After that, the temperature inside the refrigeration and cold storageshow case increases, and in the timing t3, when the inside temperatureTis reaches to the ON set temperature Ton again, the operation of thecompressor 2 is restarted and the solenoid-operated valve 4 is opened.At this moment, the opening/closing signal (control signal) becomesDC-5V also, which restarts the valve opening adjustment of themotor-driven valve 5, however, the valve opening of the valve 5 at therestarting remains as that at the stoppage of the valve openingadjustment (in the timing t2), so that increase/decrease of the valveopening of the valve 5 after restarting the operation of the compressor2 starts from the valve opening at the stoppage of the valve openingadjustment.

Therefore, the operation amount of the motor-driven valve 5 in the abovecase is calculated by deducting the valve opening at the stoppage of thevalve opening adjustment from the target valve opening calculated by thePID operation, so that, for instance, the operation amount of themotor-driven valve 5 can considerably be decreased in comparison to acase when shifted to a target valve opening from the fully-closed state.As a result, it is possible to keep the number of driving pulses of themotor-driven valve driving signal EV small to make the operation amountof the motor-driven valve 5 small, resulting in longer life of the valve5.

Next, in the timing t4, when 168 hours passes after starting count withthe timer 13 e and the count value of the timer 13 e reaches to “0”, theinitialization flag Fi is set to be “1”, which sets that initializationof the motor-driven valve 5 shall be carried out.

After that, in the timing t5, the inside temperature Tis decreases andthe temperature Tis becomes lower or equal to the OFF set temperatureToff the operation of the compressor 2 is stopped and thesolenoid-operated valve 4 is closed. In response to this, theopening/closing signal (control signal) becomes 0V, which leads a periodthat the valve control of the motor-driven valve 5 stops, so that in themotor-driven valve 5, the initialization processing is started todetermine the position of the valve body. Meanwhile, although the targetvalve opening when performing the initialization processing is set to be−α pulse as described above, the valve body of the motor-driven valve 5contact with a stopper (not shown) provided inside the motor-drivenvalve 5 when reaching to the fully-closed position, so that motion ofthe valve body is mechanically restricted, and the valve body does notmove any more in a direction that the valve 5 closes.

Then, when the initialization processing is finished, after that, in thetiming t6, the valve opening of the motor-driven valve 5 is changed tothat just before performing the initialization processing, and theinitialization flag Fi is set to be “0” as well.

Hereinafter, while the refrigeration cycle system 30 is in operation,the same operation is repeated, that is, the initialization processingof the motor-driven valve 5 is performed each time that theinitialization flag Fi is set to be “1” and the solenoid-operated valve4 is closed.

In addition, in the operation exemplified above, the solenoid-operatedvalve 4 is closed after the time measured by the timer 13 e reaches tothe initialization time It (see the timings t4, t5), so that theinitialization processing of the motor-driven valve 5 is performed afterthe solenoid-operated valve 4 is closed, on the other hand, in case thatthe solenoid-operated valve 4 is closed, reaching the time measured bythe timer 13 to the initialization time It allows the initializationprocessing to instantly be carried out.

As described above, in the present embodiment, the initialization timeIt can be set, in addition to that, each time that the time measured bythe timer 13 e reaches to the initialization time It the initializationprocessing of the motor-driven valve 5 is performed, so that not only atthe power-up but after that, the initialization processing canperiodically be carried out. As a result, even when a difference invalve opening caused by catching of a foreign substance or the like isgenerated in operation of the refrigeration cycle system 30, thedifference can periodically be modified, which allows the valve openingof the motor-driven valve 5 to accurately be controlled. Therefore, itis possible to prevent failures such as leakage of a refrigerantbeforehand, consequently, the reliability of the refrigeration and coldstorage system can be improved.

In addition, the initialization processing of the motor-driven valve 5is performed only when the refrigerant flow passage 12 a is closed afterthe solenoid-operated valve 4 is closed and the valve opening control ofthe motor-driven valve 5 through PID control is stopped, so that evenwhile the refrigeration cycle system 30 is in operation, it is possibleto perform the initialization processing without harmful affects to themotor-driven valve 5 and other devices connected with the motor-drivenvalve 5 (the compressor 2 and the like). Therefore, it is unnecessary tostop the refrigeration cycle system 30 for the initializationprocessing, which allows hindrance to the operation of the refrigerationcycle system 30 to be avoided and complexity accompanying the operationto be eliminated.

Next, a refrigeration and cold storage system and a controller of thesystem according to the third embodiment of the present invention willbe explained with reference to FIGS. 12 to 14. In FIG. 12, to the sameconstituent factors as those in FIG. 1 are attached the same symbols,and explanations thereof will be omitted. And, in the followingexplanation, the refrigeration and cold storage system according to thepresent invention is exemplarily applied to a refrigeration and coldstorage showcase used for cold reserving and displaying foods, and thelike.

FIG. 12 shows the refrigeration and cold storage system according to thethird embodiment of the present invention, this system 40 is providedwith the compressor 2, the condenser 3, the condenser fan 3 a, thesolenoid-operated valve 4, the motor-driven valve (motor-drivenexpansion valve) 5, the evaporator 6, the evaporator fan 6 a, the inlettemperature sensor 7, the outlet temperature sensor 8, the insidetemperature sensor 9, the temperature controller 10, and adegree-of-superheat controller 41.

The degree-of-superheat controller 41 is a control circuit forcontrolling valve opening of the motor-driven valve 5, and isconstructed by a microcomputer and peripheral circuits for instance.This controller 41 calculates valve opening of the motor-driven valve 5through PID control based on the degree of superheat Tsh of therefrigerant in the evaporator 6 (Tsh=the temperature Tout detected bythe outlet temperature sensor 8−the temperature Tin detected by theinlet temperature sensor 7), and outputs the motor-driven valve drivingsignal EV corresponding to the calculated valve opening to the pulsemotor of the motor-driven valve 5.

In addition, the degree-of-superheat controller 41 has functions ofdetecting opened/closed state of the solenoid-operated valve 4 bymonitoring a voltage level of the solenoid-operated valve driving signalSV, and switching presence/absence of an output of the motor-drivenvalve driving signal EV to the motor-driven valve 5 in accordance withthe opened/closed state of the solenoid-operated valve 4.

Next, the operation of the refrigeration and cold storage system 40 withthe above-mentioned construction will be explained.

Interrupt processing by the temperature controller 10 is carried out inthe same manner as the first embodiment, and the routine shown in theFIG. 3 while using a timer (not shown) and the like is performed atpredetermined intervals (every ten seconds, as an example).

Next, control operation performed by the degree-of-superheat controller41 will be explained with reference to FIGS. 12, 13. Thedegree-of-superheat controller 41 operates in synchronization with theoperation of the temperature controller 10, and in the same manner asthe controller 10, for instance, the degree-of-superheat controller 41performs a routine shown in the FIG. 13 every ten seconds, as anexample.

When the interrupt processing is started, as shown in FIG. 13, thedegree-of-superheat controller 41 firstly references thesolenoid-operated valve driving signal SV outputted from the temperaturecontroller 10, and judges whether or not the solenoid-operated valve 4is opened. As a result of the judgment, in case that the valve 4 isopened (Step S81: Yes), the degree-of-superheat controller 41 takes inrefrigerant temperatures Tin, Tout at the inlet and outlet of theevaporator 6 respectively (Steps S82, S83) to calculate the presentdegree-of-superheat Tsh (=Tout−Tin) (Step S84).

Next, a deviation e(t) (=Ts−Tsh) between a set degree-of-superheat(target value of the degree of superheat Tsh) Ts and the presentdegree-of-superheat Tsh is calculated (Step S85), and based on a set ofthe deviation e in the past, the proportional band PB, the integrationtime Ti and the derivative time Td, the operation amount m(t) of thevalve opening is calculated with a PID (proportional, integral anddifferential) calculation in accordance with the above formula 1 (StepS86).

This calculates a target valve opening that the motor-driven valve 5should reach to, and the degree-of-superheat controller 41 specifies thenumber of driving pulses such that a valve opening of the valve 5becomes the target valve opening, and outputs the motor-driven valvedriving signal EV to the valve 5 to increase/decrease the valve openingof the valve 5 (Step S87).

On the other hand, as a result of the above judgment in Step S81, incase that the solenoid-operated valve 4 is closed (Step S81: No), anyprocession is not performed, and changing the valve opening of themotor-driven valve 5 and the like are not carried out.

Next, operations of the solenoid-operated valve 4 and the motor-drivenvalve 5, when operation/stoppage of the compressor 2 is switched, willbe exemplarily explained mainly with reference to FIG. 14.

In the timing t1, when the inside temperature Tis becomes higher orequal to the ON set temperature Ton, the compressor 2 is operated andthe solenoid-operated valve 4 is opened to open the refrigerant flowpassage 12 a. Further, in response to the opening the solenoid-operatedvalve 4, the valve opening adjustment of the motor-driven valve 5 basedon a PID calculation is started to adjust flow rate of a refrigerantcirculating in the refrigeration cycle. The operation of the compressor2, the opening of the solenoid-operated valve 4 and the valve openingadjustment of the motor-driven valve 5 are continuously performed untilthe inside temperature Tis is higher than the OFF set temperature Toffeven if the inside temperature Tis becomes lower or equal to the ON settemperature Ton.

Then, the temperature inside the refrigeration and cold storage showcase decreases, and in the timing t2, when the inside temperature Tisreaches to the OFF set temperature Toff, the operation of the compressor2 is stopped and the solenoid-operated valve 4 is closed to close therefrigerant flow passage 12 a. In addition, in response to the closingthe solenoid-operated valve 4, outputting the motor-driven valve drivingsignal EV to the motor-driven valve 5 is stopped (the number of drivingpulses is set to be zero), and the valve opening adjustment of the valve5 is suspended. As a result, the valve opening of the motor-driven valve5 remains as that at the stoppage of the valve opening adjustment,hereinafter, until the valve opening adjustment is restarted, thecondition is maintained.

After that, the temperature inside the refrigeration and cold storageshow case increases, and in the timing t3, when the inside temperatureTis reaches to the ON set temperature Ton again, the operation of thecompressor 2 is restarted and the solenoid-operated valve 4 is opened.At this moment, the valve opening adjustment of the motor-driven valve 5is restarted, however, the valve opening of the valve 5 at therestarting remains as that at the stoppage of the valve openingadjustment (in the timing t2), so that increase/decrease of the valveopening of the valve 5 after restarting the operation of the compressor2 starts from the valve opening at the stoppage of the valve openingadjustment.

Therefore, the operation amount of the motor-driven valve 5 in the abovecase is calculated by deducting the valve opening at the stoppage of thevalve opening adjustment from the target valve opening calculated by thePID operation, so that, for instance, the operation amount of themotor-driven valve 5 can considerably be decreased in comparison to acase when shifted to a target valve opening from the fully-closed state.As a result, it is possible to keep the number of driving pulses of themotor-driven valve driving signal EV small, which allows the consumptionof the number of driving pulses accompanying the switching ofoperation/stoppage of the compressor 2 to sharply be reduced.

As mentioned above, in the embodiment, the solenoid-operated valve 4 ismounted between the condenser 3 and the evaporator 6, in addition tothat, when the operation of the compressor 2 is stopped, thesolenoid-operated valve 4 is closed and the valve opening of themotor-driven valve 5 is maintained as that at the stoppage of theoperation of the compressor 2 as well, and when the operation of thecompressor 2 is restarted, the solenoid-operated valve 4 is opened andthe valve opening control of the motor-driven valve 5 is started fromthe valve opening at the stoppage of the operation of the compressor 2as well, which makes the fully-closing operation of the motor-drivenvalve 5 when stopping the compressor 2 and the opening operation of themotor-driven valve 5 when starting the compressor 2 unnecessary, whilepreventing the inside temperature from rising when the operation of thecompressor 2 is stopped.

As a result, it becomes unnecessary to largely change the valve openingof the motor-driven valve 5 each time that the operation/stoppage of thecompressor 2 is switched, which remarkably reduces the consumption ofthe number of driving pulses. This allows the life of the motor-drivenvalve 5 to be lengthened, consequently, the reliability of therefrigeration and cold storage system to be improved.

The embodiments of the present invention are explained above, however,this invention is not limited to the above constructions, and variouschanges can be made in the scope of the invention described in claims.

For example, in the first to the third embodiments, although systemscontrolling the temperature inside of a refrigeration and cold storageshowcase are shown as the refrigeration cycle systems 1, 30 and 40, thisinvention can widely be applied to other temperature adjustment systemssuch as air conditioners.

Moreover, in the first to the third embodiments, valve opening of anexpansion valve is controlled in a refrigeration cycle, as an example,however, this invention can also be applied to control of a flow controlvalve (motor-driven valve) in a hot gas by-pass circuit of arefrigeration cycle.

Furthermore, in the first and second embodiments, although wiredcommunication is exemplified as a type of communication between themicroprocessors 13 of the degree-of-superheat controllers 11, 31 and thePCs 23, it may be possible to utilize radio communication for connectingthe microprocessors 13 and the PCs 23. This is also applicable to themicroprocessor (not shown) of the degree-of-superheat controller 41according to the third embodiment.

In the first to the third embodiments, the solenoid-operated valve 4 isdisposed upstream of the motor-driven valve 5 (between the condenser 3and the motor-driven valves 5), so long as between the condenser 3 andthe evaporator 6, the position where the solenoid-operated valve 4 isdisposed is not limited in particular, and the valve 4 may be disposeddownstream of the motor-driven valve 5 (between the motor-driven valve 5and the evaporator 6).

Further, in the first to the third embodiments, though the temperaturecontroller 10 and the degree-of-superheat controllers 11, 31, 41 areseparately constructed for convenience of explanation, these controllerscan be integrated as a single microcomputer and others. In such a case,information on opened/closed state of the solenoid-operated valve 4 fromthe temperature controller 10 toward the degree-of-superheat controllers11, 31, and 41 (the solenoid-operated valve driving signal SV) can bemanaged through inner procession of the microcomputer.

Although outputting the solenoid-operated valve driving signal SV to thedegree-of-superheat controller 41 allows opened/closed state of thesolenoid-operated valve 4 to be informed to the degree-of-superheatcontroller 41 in the first to the third embodiments, thesolenoid-operated valve driving signal SV is not always used, but othersignal capable of informing the opened/closed state of thesolenoid-operated valve 4 can be outputted to the degree-of-superheatcontroller 41.

Still further, in the first to the third embodiments, valve opening ofthe motor-driven valve 5 is exemplarily controlled by PID control, inaddition to that, P (proportional) control, PI (proportional andintegral) control, or PD (proportional and differential) control can beused.

EXPLANATION OF REFERENCE NUMBERS

-   -   1 refrigeration cycle system    -   2 compressor    -   3 condenser    -   3 a condenser fan    -   4 solenoid-operated valve    -   5 motor-driven valve    -   5 a pulse motor    -   6 evaporator    -   6 a evaporator fan    -   7 inlet temperature sensor    -   8 outlet temperature sensor    -   9 inside temperature sensor    -   10 temperature controller    -   11 degree-of-superheat controller    -   12 conduit    -   12 a refrigerant flow passage    -   13 micro processor    -   13 a A/D converter    -   13 b CPU    -   13 c ROM    -   13 d RAM    -   13 e timer    -   13 f I/O    -   14 inlet temperature detecting circuit    -   15 outlet temperature detecting circuit    -   16 motor-driven valve driving circuit    -   16 a driver IC    -   17 input circuit    -   17 a up switch    -   17 b down switch    -   17 c set switch    -   17 d enter switch    -   18 display circuit    -   18 a temperature displaying element    -   18 b valve opening displaying element    -   18 c LEDs    -   19 display driver circuit    -   20 memory circuit    -   21 control signal input circuit    -   22 communication signal conversion circuit    -   23 PC    -   23 a connection cable    -   30 refrigeration cycle system    -   31 degree-of-superheat controller    -   34 inlet temperature detecting circuit    -   34 a bridge circuit    -   34 b amplifying circuit    -   35 outlet temperature detecting circuit    -   35 a bridge circuit    -   35 b amplifying circuit    -   40 refrigeration and cold storage system    -   41 degree-of-superheat controller

1. A valve controller for detecting one of temperature and pressure of arefrigeration cycle based on an output value of a sensor and controllingvalve opening of a motor-driven valve based on a detected value,comprising: valve opening setting means for performing one of settingand changing emergency valve opening of the motor-driven valve; andvalve opening controlling means for stopping, when an abnormality occursin the sensor, movement of the motor-driven valve at an emergency valveopening to which one of the setting and the changing is performedthrough the valve opening setting means.
 2. The valve controller asclaimed in claim 1, wherein said emergency valve opening is larger thana valve opening in a fully-closed state and smaller than a valve openingin a fully-opened state, and is a valve opening capable of continuingoperation of the refrigeration cycle.
 3. The valve controller as claimedin claim 1, wherein said sensor is one of a temperature sensor fordetecting temperature of a controlled object and a pressure sensor fordetecting pressure of a refrigerant circulating in the refrigerationcycle.
 4. The valve controller as claimed in claim 1, further comprisingcommunication means for performing one of the setting and the changingthe emergency valve opening from an outer device by utilizing one ofwire communication and wireless communication.
 5. The valve controlleras claimed in claim 1, wherein said motor-driven valve is one of anexpansion valve in the refrigeration cycle and a flow control valve in ahot gas bypass circuit of the refrigeration cycle.
 6. A valve controllerfor controlling valve opening of a motor-driven valve and initializationprocessing of the motor-driven valve, comprising: valve openingcontrolling means for controlling valve opening of the motor-drivenvalve; initialization time setting means for setting initialization timethat determines intervals for performing the initialization processingof the motor-driven valve; time measuring means for measuring elapsedtime; and initialization controlling means for performing theinitialization processing of the motor-driven valve when elapsed timethat is measured by the time measuring means reaches to theinitialization time and the valve opening controlling means stops valveopening control of the motor-driven valve as well.
 7. The valvecontroller as claimed in claim 6, wherein said valve opening controllingmeans calculates a deviation between a detected temperature of an objectto be adjusted for its temperature and a target temperature; calculatesa target valve opening based on the deviation; and controls valveopening of the motor-driven valve so as to be the target valve opening.8. The valve controller as claimed in claim 7, wherein said motor-drivenvalve is a motor-driven expansion valve in a refrigeration cycle, andsaid detected temperature is a degree of superheat.
 9. The valvecontroller as claimed in claim 8, wherein in said refrigeration cycleare connected a compressor, a condenser, a motor-driven valve and anevaporator in this order, and operation/stoppage of the compressor isswitched in accordance with a temperature of a controlled object, andsaid initialization controlling means performs the initializationprocessing of the motor-driven valve when elapsed time that is measuredby the time measuring means reaches to the initialization time and thecompressor stops as well.
 10. The valve controller as claimed in claim9, wherein said refrigeration cycle is provided with a solenoid-operatedvalve disposed between the condenser and the evaporator to open/close arefrigerant flow passage between them; said valve controller is providedwith solenoid-operated valve controlling means for closing thesolenoid-operated valve when operation of the compressor stops and foropening the solenoid-operated valve when operation of the compressor isrestarted; and said initialization controlling means performsinitialization processing of the motor-driven valve when elapsed timethat is measured by the time measuring means reaches to theinitialization time and the solenoid-operated valve is closed as well.11. The valve controller as claimed in claim 10, wherein when thesolenoid-operated valve is closed said valve opening controlling meansmaintains a valve opening of the motor-driven valve at an opening whenoperation of the compressor stops, and when the solenoid-operated valveis opened said valve opening controlling means starts valve openingcontrol of the motor-driven valve from the opening at the stoppage ofthe compressor.
 12. The valve controller as claimed in claim 6, furthercomprising communication means for setting the initialization time froman outer device by utilizing one of wire communication and wirelesscommunication.
 13. A valve controlling method of controlling valveopening of a motor-driven valve as well as initialization processing ofthe motor-driven valve, comprising the steps of: measuring elapsed timeand judging whether or not the measured elapsed time reaches to aninitialization time that determines intervals for performing theinitialization processing of the motor-driven valve; and performing theinitialization processing of the motor-driven valve when said measuredelapsed time reaches to the initialization time, and valve openingcontrol of the motor-driven valve stops as well.
 14. A refrigeration andcold storage system, in which a compressor, a condenser, a motor-drivenexpansion valve and an evaporator are connected in this order, saidrefrigeration and cold storage system switching operation/stoppage ofthe compressor in accordance with a temperature of a controlled object,and further comprising a solenoid-operated valve disposed between thecondenser and the evaporator to open/close a refrigerant flow passagebetween them, wherein when operation of the compressor is stopped, thesolenoid-operated valve is closed and a valve opening of themotor-driven expansion valve is maintained at an opening when theoperation of the compressor stops, and when the operation of thecompressor is restarted, the solenoid-operated valve is opened and valveopening control of the motor-driven expansion valve starts from theopening at the stoppage of the compressor.
 15. A controller forcontrolling operation of a refrigeration and cold storage system, saidrefrigeration and cold storage system having a refrigeration cycle inwhich a compressor, a condenser, a motor-driven expansion valve and anevaporator are connected in this order and a solenoid-operated valvedisposed between the condenser and the evaporator to open/close arefrigerant flow passage between them, said refrigeration and coldstorage system switching operation/stoppage of the compressor inaccordance with a temperature of a controlled object, wherein saidcontroller, when stopping the operation of the compressor, closes thesolenoid-operated valve and maintains a valve opening of themotor-driven expansion valve at an opening when the operation of thecompressor stops, and when restarting the operation of the compressor,opens the solenoid-operated valve and starts valve opening control ofthe motor-driven expansion valve from the opening at the stoppage of thecompressor.
 16. The controller of the refrigeration and cold storagesystem as claimed in claim 15, further comprising: a first controlsection for switching operation/stoppage of the compressor in accordancewith the temperature of the controlled object and controllingopening/closing of the solenoid-operated valve; and a second controlsection for controlling valve opening of the motor-driven expansionvalve in accordance with a degree of superheat of a refrigerant flowingthe evaporator, wherein said second control section monitorsopened/closed state of the solenoid-operated valve and stops outputtinga driving signal for the valve opening control in accordance with theclosing of the solenoid-operated valve.
 17. The controller of therefrigeration and cold storage system as claimed in claim 16, whereinthe first control section operates the compressor when the temperatureof the controlled object is higher or equal to a first setting valuethat is set at a predetermined temperature, and the first controlsection stops operation of the compressor when the temperature of thecontrolled object is lower or equal to a second setting value that islower than the first setting value.
 18. The controller of therefrigeration and cold storage system as claimed in claim 15, whereinthe refrigeration and cold storage system is used for a refrigerationand cold storage showcase for foods, and the temperature of controlledobject is inside temperature of the refrigeration and cold storageshowcase.
 19. A method of controlling operation of a refrigeration andcold storage system, said refrigeration and cold storage system having arefrigeration cycle in which a compressor, a condenser, a motor-drivenexpansion valve and an evaporator are connected in this order and asolenoid-operated valve disposed between the condenser and theevaporator to open/close a refrigerant flow passage between them, saidrefrigeration and cold storage system switching operation/stoppage ofthe compressor in accordance with a temperature of a controlled object,wherein said method comprising the steps of: when stopping the operationof the compressor, closing the solenoid-operated valve and maintaining avalve opening of the motor-driven expansion valve at an opening when theoperation of the compressor stops; and when restarting the operation ofthe compressor, opening the solenoid-operated valve and starting valveopening control of the motor-driven expansion valve from the opening atthe stoppage of the compressor.